2,026 research outputs found
Polypyrrole Coated PET Fabrics for Thermal Applications
Polypyrrole can be chemically synthesized on PET fabrics, giving rise to textiles with high electric conductivity. These textiles are suitable for several applications from antistatic films to electromagnetic interference shielding devices. Here we discuss the thermal-electric performance and the heat generation of polypyrrole coated PET fabric samples, previously studied because of their electric conductivity and electromagnetic interference shielding effectiveness. The measured Seebeck effect is comparable with that of metallic thermocouples. Since polypyrrole shows extremely low thermal diffusivities regardless of the electrical conductivity, the low thermal conductivity gives significant advantage to the thermoelectric figure-of-merit ZT, comparable with that of some traditional inorganic thermoelectric materials. The heat generation is also investigated for possible heating textile devices. The results confirm polypyrrole as a prom- ising material for thermal electric applications due to its easy preparation in low cost processin
Emergence of turbulence in an oscillating Bose-Einstein condensate
We report on the experimental observation of vortices tangle in an atomic BEC
of Rb-87 atoms when an external oscillatory perturbation is introduced in the
trap. The vortices tangle configuration is a signature of the presence of a
turbulent regime in the cloud. We also show that this turbulent cloud has
suppression of the aspect ratio inversion typically observed in quantum
degenerate bosonic gases during free expansion. Instead, the cloud expands
keeping the ratio between their axis constant. Turbulence in atomic superfluids
may constitute an alternative system to investigate decay mechanisms as well as
to test fundamental theoretical aspects in this field.Comment: accepted for Phys. Rev. Let
Thermal electric effects and heat generation in polypyrrole coated PET fabrics
Polypyrrole chemically synthesized on PET gives rise to textiles with a high
electric conductivity, suitable for several applications from antistatics to
electromagnetic interference shielding devices. Here, we discuss investigations
on thermal electric performances of the polypyrrole coated PET in a wide range
of temperatures above room temperature. The Seebeck coefficient turns out to be
comparable with that of metal thermocouple materials. Since polypyrrole shows
extremely low thermal diffusivities regardless of the electrical conductivity,
the low thermal conductivity gives significant advantage to the thermoelectric
figure-of-merit ZT, comparable with that of some traditional inorganic
thermoelectric materials. The heat generation is also investigated for possible
heating textile devices.Comment: 12 pages and 9 figure
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